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Shockley's Rock cress

Lemmon's rock-cress, Lemmon's suncress, wind-blown suncress

Habit Perennials; usually short-lived; sexual; caudex not woody, (rarely with persistent, crowded leaf bases). Perennials; long-lived; (somewhat cespitose); sexual or apomictic; caudex woody.
Stems

usually 1 per caudex branch, arising from center of rosette near ground surface, (0.8–)2–5 dm, densely pubescent proximally, trichomes short-stalked, 7–12-rayed, 0.1–0.2 mm, densely to sparsely pubescent distally.

usually 1 per caudex branch, arising from center of rosette near ground surface, or arising laterally proximal to sterile shoots, 0.5–2(–2.5) dm, glabrous or sparsely pubescent proximally, trichomes short-stalked, 2–6-rayed, 0.1–0.2 mm, glabrous distally.

Basal leaves

blade oblanceolate, 3–10 mm wide, margins entire, not ciliate, surfaces densely pubescent, trichomes short-stalked, 7–12-rayed, 0.1–0.2 mm.

blade oblanceolate to obovate, 1.5–5 mm wide, margins usually entire, rarely slightly dentate, ciliate along petiole, surfaces densely to sparsely pubescent, trichomes short-stalked, 3–9-rayed, 0.1–0.2 mm.

Cauline leaves

14–60, concealing stem for most of length;

blade auricles 0.5–4 mm, surfaces of distalmost leaves densely pubescent.

2–8(–12), not concealing stem;

blade auricles absent or 0.1–0.5 mm, surfaces of distalmost leaves glabrous or sparsely pubescent.

Racemes

20–70-flowered, usually unbranched.

3–12(–17)-flowered, usually unbranched.

Flowers

ascending at anthesis;

sepals pubescent;

petals lavender, 6–9 × 0.8–1.2 mm, glabrous;

pollen ellipsoid.

divaricate-ascending at anthesis;

sepals glabrous or sparsely pubescent;

petals purple to lavender, 3.5–6 × 1–1.5 mm;

pollen ellipsoid or spheroid.

Fruiting pedicels

divaricate-ascending, straight, 7–28 mm, pubescent, trichomes appressed, branched.

divaricate-ascending to slightly descending, usually slightly recurved, rarely straight, 2–6 mm, glabrous or sparsely pubescent, trichomes appressed, branched.

Fruits

divaricate-ascending, not appressed to rachis, not secund, usually curved, rarely straight, edges parallel, 4.5–11 cm × 1.5–2 mm;

valves glabrous or sparsely pubescent throughout;

ovules 140–190 per ovary;

style 0.05–0.6 mm.

divaricate-ascending to slightly descending, not appressed to rachis, secund, straight or curved, edges parallel, (1.6–) 2–4.4 cm × 1.6–2.3 mm;

valves glabrous;

ovules 28 40(–44) per ovary;

style 0.1–0.2 mm.

Seeds

sub-biseriate, 1–1.3 × 0.7–0.8 mm;

wing distal or, rarely, absent, 0.05–0.1 mm wide.

uniseriate, 1.3–2 × 1–1.5 mm;

wing continuous, 0.1–0.5 mm wide.

2n

= 14.

Boechera shockleyi

Boechera lemmonii

Phenology Flowering Apr–May. Flowering Jun–Aug.
Habitat Rock outcrops (primarily dolomite) and gravelly soil in desert scrub, sagebrush, and pinyon-juniper woodlands Cliffs, talus slopes, and gravelly soil in alpine and subalpine habitats
Elevation 1200-2200 m (3900-7200 ft) 2100-4400 m (6900-14400 ft)
Distribution
from FNA
CA; NV; UT
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC; YT
[WildflowerSearch map]
[BONAP county map]
Discussion

Boechera shockleyi is a distinctive sexual species recognizable by the combination of strongly overlapping cauline leaves, a dense covering of minute, 7–12-rayed trichomes, and relatively long, curved, divaricate-ascending fruits with sub-biseriate seeds. It is most similar to B. inyoensis, but differs from that species in its narrower (0.8–1.2 versus 1.2–2 mm) petals, eciliate basal leaves with smaller (0.1–0.2 versus 0.2–0.7 mm) trichomes, greater number (140–190 versus 74–134) of ovules per ovary, and shorter (1–1.3 versus 1.7–2 mm) seeds with distal (versus continuous) wings.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Boechera lemmonii is easily recognized by its combination of secund fruits, mat-forming habit, purplish sepals, and obovate-oblanceolate cauline leaves. Both sexual and apomictic collections are known; further study is needed to determine whether they truly are conspecific. The taxa traditionally treated as Arabis (Boechera) lemmonii vars. depauperata, drepanoloba, and paddoensis are apomictic hybrids here recognized as distinct species (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 406. FNA vol. 7, p. 388.
Parent taxa Brassicaceae > tribe Boechereae > Boechera Brassicaceae > tribe Boechereae > Boechera
Sibling taxa
B. acutina, B. arcuata, B. atrorubens, B. bodiensis, B. breweri, B. burkii, B. calderi, B. californica, B. canadensis, B. cascadensis, B. cobrensis, B. collinsii, B. consanguinea, B. constancei, B. covillei, B. crandallii, B. cusickii, B. davidsonii, B. dentata, B. depauperata, B. dispar, B. divaricarpa, B. drepanoloba, B. duchesnensis, B. elkoensis, B. evadens, B. falcatoria, B. falcifructa, B. fecunda, B. fendleri, B. fernaldiana, B. formosa, B. fructicosa, B. glareosa, B. glaucovalvula, B. goodrichii, B. gracilenta, B. gracilipes, B. grahamii, B. gunnisoniana, B. harrisonii, B. hastatula, B. hoffmannii, B. holboellii, B. horizontalis, B. howellii, B. inyoensis, B. johnstonii, B. koehleri, B. laevigata, B. languida, B. lasiocarpa, B. lemmonii, B. lignifera, B. lincolnensis, B. lyallii, B. macounii, B. microphylla, B. missouriensis, B. nevadensis, B. ophira, B. oxylobula, B. paddoensis, B. pallidifolia, B. parishii, B. pauciflora, B. paupercula, B. peirsonii, B. pendulina, B. pendulocarpa, B. perennans, B. perstellata, B. pinetorum, B. pinzliae, B. platysperma, B. polyantha, B. porphyrea, B. pratincola, B. puberula, B. pulchra, B. pusilla, B. pygmaea, B. quebecensis, B. rectissima, B. repanda, B. retrofracta, B. rigidissima, B. rollei, B. rollinsiorum, B. rubicundula, B. saximontana, B. schistacea, B. serotina, B. serpenticola, B. shevockii, B. sparsiflora, B. spatifolia, B. stricta, B. subpinnatifida, B. suffrutescens, B. texana, B. tiehmii, B. tularensis, B. ultra-alsa, B. villosa, B. williamsii, B. xylopoda, B. yorkii
B. acutina, B. arcuata, B. atrorubens, B. bodiensis, B. breweri, B. burkii, B. calderi, B. californica, B. canadensis, B. cascadensis, B. cobrensis, B. collinsii, B. consanguinea, B. constancei, B. covillei, B. crandallii, B. cusickii, B. davidsonii, B. dentata, B. depauperata, B. dispar, B. divaricarpa, B. drepanoloba, B. duchesnensis, B. elkoensis, B. evadens, B. falcatoria, B. falcifructa, B. fecunda, B. fendleri, B. fernaldiana, B. formosa, B. fructicosa, B. glareosa, B. glaucovalvula, B. goodrichii, B. gracilenta, B. gracilipes, B. grahamii, B. gunnisoniana, B. harrisonii, B. hastatula, B. hoffmannii, B. holboellii, B. horizontalis, B. howellii, B. inyoensis, B. johnstonii, B. koehleri, B. laevigata, B. languida, B. lasiocarpa, B. lignifera, B. lincolnensis, B. lyallii, B. macounii, B. microphylla, B. missouriensis, B. nevadensis, B. ophira, B. oxylobula, B. paddoensis, B. pallidifolia, B. parishii, B. pauciflora, B. paupercula, B. peirsonii, B. pendulina, B. pendulocarpa, B. perennans, B. perstellata, B. pinetorum, B. pinzliae, B. platysperma, B. polyantha, B. porphyrea, B. pratincola, B. puberula, B. pulchra, B. pusilla, B. pygmaea, B. quebecensis, B. rectissima, B. repanda, B. retrofracta, B. rigidissima, B. rollei, B. rollinsiorum, B. rubicundula, B. saximontana, B. schistacea, B. serotina, B. serpenticola, B. shevockii, B. shockleyi, B. sparsiflora, B. spatifolia, B. stricta, B. subpinnatifida, B. suffrutescens, B. texana, B. tiehmii, B. tularensis, B. ultra-alsa, B. villosa, B. williamsii, B. xylopoda, B. yorkii
Synonyms Arabis shockleyi Arabis lemmonii, Arabis bracteolata, Arabis canescens var. latifolia, Arabis codyi, Arabis egglestonii, Arabis kennedyi, Arabis latifolia, Arabis oreocallis, Arabis polyclada, Arabis semisepulta
Name authority (Munz) Dorn: Brittonia 55: 3. (2003) (S. Watson) W. A. Weber: Phytologia 51: 370. (1982)
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